the TaskButton has a window to be its property,and when user click taskButton,the window will show up on some conditions.I think we can also show up the window by a listener which will listen the event fired by taskbutton just like the Shortcut and the MenuItem doing, in this way, it is not necessary that there is a property window in Class TaskButton.The sample doesn't do it like this,it just override the onClick method of the TaskButton and show up its property window when click it.My question is that for what purpose the taskButton does't has a listener? Is it possible that all the windows in the deskTop are independent and no component has a window property just to keep in line with the Shortcut and MenuItem.